I recieved emails from Microsoft to update Authentication to Oauth as support for basic authentication will soon cease. Whilst I have not been experiencing any issues, after following the instructions, also provided here: https://support.mozilla.org/en-US/kb/microsoft-oauth-authentication-and-thunderbird-202, I now have an unusable Thunderbird client. This is because I am having to keep authenticating my outlook accounts (I have about ~100 email accounts). They pop up one after the other for each account. I believe I went through all the troubleshooting steps but to no joy. I did notice however, when the "Enter your credentials....." pop up box appears and I go through the motions of authenticating my account and TB against my Microsoft account, the following entry appears under the Settings > Saved Passwords > Saved Logins > "Provider" column for that account: oauth://login.microsoftonline.com (https://outlook.office.com/IMAP.AccessAsUser.All https://outlook.office.com/POP.AccessAsUser.All https://outlook.office.com/SMTP.Send offline_access) The credentials include a very long auto generated password starting similar to "M.C533_BAY.0.U.-........" A couple of things to note now regarding the oauth entry: 1. It ''possibly'' does not always get created when re-authenticating 2. After quitting TB and then re-launching TB, it dissapears So the solution would be to somehow ensure this entry is created and it ''sticks'' even after quitting TB, since for those accounts that include this I do not have get the "Enter your credentials....." pop up box. Is this something TB can investigate?